1. Field of the Invention
The present invention relates to a method for the preparation of cross-linked enzyme aggregates, more specifically to a method for the preparation of hybrid cross-linked enzyme-silica aggregates.
2. Description of Related Art
Methods for the preparation of cross-linked enzyme aggregates are known in the art. Such a method is, for example, described in EP 1,088,887 A1, and discloses the production of crosslinked enzyme aggregates by precipitating an enzyme from solution with a precipitating agent whereby aggregates are formed, and crosslinking the precipitated enzyme with a crosslinking agent. It is indicated that, during aggregation, a carrier may be present. Any information about the specific nature of a suitable carrier, and at which stage the carrier should be added, is missing in this reference.
The possibilities of varying properties afforded by such known methods is nevertheless limited, and consequently such methods often result in cross-linked enzyme aggregates (called CLEAs) with properties, in particular activity and colloidal behavior, that are not optimal for the ultimate purpose of the cross-linked enzyme aggregates.
Further, methods for the immobilization of enzymes on a carrier are also known, for example in U.S. Pat. No. 5,002,884 to Kobayashi et al., and U.S. Pat. No. 5,405,766 to Kallury et al. Kobayashi and Kallury teach that enzymes can be immobilized on silica, as a carrier, the surface of which has been modified by pretreatment with an alkoxysilane. The enzyme is thus anchored onto the modified carrier surface. The enzyme loading of the obtained aggregates is rather low.